US Patent Application Publication 2007/0265526, whose disclosure is incorporated herein by reference, describes a magnetic position tracking system for performing a medical procedure on a patient who is positioned on an upper surface of a table. The system includes a location pad, which is positioned on the upper surface of the table beneath the patient. The location pad includes one or more field generators, which are operative to generate respective magnetic fields and are arranged so that a thickness dimension of the location pad is no greater than 3 centimeters. A position sensor is fixed to an invasive medical device for insertion into a body of the patient, and is arranged to sense the magnetic fields so as to measure a position of the medical device in the body.
U.S. Pat. No. 5,425,367, whose disclosure is incorporated herein by reference, describes a system for externally locating the depth and orientation of a catheter in tissue with an external probe which generates a virtual rotating magnetic field. The catheter includes an inductive coil for developing an induced signal in response to the virtual rotating magnetic field. An indicating device such as a light bar display or digital readout indicates the strength of the induced signal for locating, independently of the relative angular orientation of the probe and the catheter, the depth in the tissue of the catheter.
U.S. Pat. No. 6,223,066, whose disclosure is incorporated herein by reference, describes an elongate medical probe, having proximal and distal ends, whose position is tracked within the body of a subject. The probe includes a magnetic-field responsive optical element adjacent to the distal end, which modulates light passing therethrough responsive to an externally-applied magnetic field. The probe also includes a fiberoptic coupled to receive modulated light from the optical element and convey it to the proximal end of the probe for analysis of the modulation.
U.S. Pat. No. 6,335,617, whose disclosure is incorporated herein by reference, describes a method for calibrating a magnetic field generator, including fixing one or more magnetic field sensors to a probe in known positions and orientations and selecting one or more known locations in the vicinity of the magnetic field generator. The magnetic field generator is driven so as to generate a magnetic field. The probe is moved in a predetermined, known orientation to each of the one or more locations, and signals are received from the one or more sensors at each of the one or more locations. The signals are processed to measure the amplitude and direction of the magnetic field, at the respective positions of the one or more sensors and to determine calibration factors relating to the amplitude and direction of the magnetic field in the vicinity of the magnetic field generator.
PCT Publication WO/2013/149683, whose disclosure is incorporated herein by reference, describes systems, devices and methods for the ablation of a ablation of the wall of one or more pulmonary veins (PV) from the inside, preferably transmural ablation and preferably at the level of the antrum. One or more implant devices can be implanted in the vessels and can subsequently be heated by external energy-providing means.